It is common for owners to mount objects such as bicycles onto the rear of their vehicles, usually using a special mounting rack. This tends to obscure some or all of the rear signalling lights which can be dangerous and/or illegal.
Trailer boards are available for mounting to the rear of vehicle trailers or caravans, which trailer boards comprise an elongate board carrying at least a basic set of signalling lights such as tail lights and indicators. The trailer board has a cable terminating with a special plug adapted to detachably connect to an electrical socket on the car, e.g. a 12N plug and socket system. This physical connection takes power from the car battery, and multiple signals from the car's signalling system. The socket on the car needs to be fitted and wired to its electrical and signalling system by a trained installer, and is typically associated with fitting a tow bar attachment or similar. When connected, the trailer board replicates signalling from the car to the signalling lights to ensure that following vehicles can see them.
One issue with trailerboards of the prior art is that the power available from a 12n socket would be close to power capacity. None of the prior art disclose the concept of introducing a micro controller for both TX and reverse sensors retrofit which control both units and also filter out unwanted light in turn omitting any unwanted signals.
Most vehicles are not sold with readily available electrical connectors, particularly external connectors, for relaying signalling to the rear of the vehicle. For owners that simply wish to mount bicycles or similar objects on an occasional basis, there is little or no option for ensuring compliance and safety requirements without having a specially installed tow bar system.